Pigment and method of making same



Patented Sept. 24, 1940 1 UNITED STATES PATENT ,OFFICE PIGDIENT AND METHOD OF MAKING SAME William D. Stillwell, Cleveland Heights, Ohio, assigner to The Harshaw Chemical Company, Elyria, Ohio, a corporation of Ohio.

No Drawing. Application December 31, 1937 Serial No. 182,853

8 Claims. (01. 106--36.2l

For many years the main yellow colorants going, and having a lemon-yellow color not available in ceramics have been from the followhitherto available with lead antimonate, and being groups: (a) cadmium sulphide; (b) rutile ing less costly than lead antimonate containing stains; (c) uranium stains; (d) vanadium-tin tin oxide; and coupled with such advantages is a stains; (e) iron stains; (f) chromium stains; (g) greater stability than existent in cadmium sul- 5v lead-antimony (Naples yellow) stains; and (h) phide yellows, together with lower cost as comsilver stains. More recently, an antimonypared therewith. titania-chromium stain, and a ceria-titania stain To the accomplishment of the foregoing and have been described. Most of these stains are related ends, the invention, then, comprises the 10 quite specific in action, and very limited in their features hereinafter fully described, andparti'cu- HT usage. A yellow uranium stain for example, is larly pointed out in the claims, the following deused mostly in glass and glazes, while an antiscrip-tion setting forth in detail certain illustramony-titania-chromium stain is practically limtive embodiments of the invention, these being ited to body stain, and cadmium sulphide because indicative however, of but a few of the various I of its low decomposition temperature, is limited ways in which the principle of the invention may to low-fired glazes and vitreous enamel. In the be employed.

field of vitreous enamels for example, only three I have found that a new color is formed from of the afore-named stains furnish a color that oxides, of lead, antimony and titanium in specific n really be i n ted as y llow. These are proportions, this new color coinciding closely with cadmium sulphide, chromates, and Naples yellow. the molecular formula 4PbO.SbzO5.4TiO-i. Any

Cadmium sulphide yields a strong lemon-yellow divergence from this formula results in lowering enam l ain, but h s h v ry u ir l h rthe desired qualities of this stain in vitreous acteristic of instability. Because of its low deenamels and glazes, in the following respects: composition temperature in vitreous enamels it is (1) o increasing the titanium dioxide content,

troublesome and unreliable, but because of its th yellow loses t th; (2) on decreasing t brilli nt l m -yell w c0 0 n inu s to find titanium dioxide content, the mass-tone becomes W s e though e p Special enamel more orange in color, and the stain in enamels fri S re Ofte u ed Wi t s typ of 1 High has much less strength; (3) on increasing the percentages f cadmium phi e in e l are antimony oxide content, the yellowrapidly loses prone to Cause scumming- A number of strength and increases in opacity; (4) on de- 30 mates, such as o ead, u St eta, creasing antimony oxide content, the yellow loses have been used as colorants in vitreous enamels, t th nd opacity; (5) on increasing the lead b t ese a e y Weak tinctolially. because oxide content, the yellow becomes more orange in of e S Y in the mill liquor 0f Vitreous color and loses the desirable lemon tone, and a at) enamels they usu Yield enamels having an larger increase in lead oxide causes the color to desirable scum. The reaction between lead oxide flux on firing; (6) on decreasing the lead oxide and antimony oxide to form lead antimonate or t t t yenow 1059s trength rapidly it Naples Yellow is Well known in the While crease in opacity. Practically, therefore, to at-' 40 the masson of su h p m re y strong. tain the desired color without dilution or change,

th s material has ostly l ttle th s a the oxides are maintained substantially within 40 ceramic pigment. It is common practice there the limits of PbO 50-70 per cent, SbzOs 14-26 per fore to incorporate about 10 per cent of alumina cent, and TiOz, 14-26 per cent. or tin oxide or combinations thereof in the Naples For the materials in making up the present yellow during manufacture, these materials being pigment, convenient sources of the elements conknown in the trade as stabilizers, and the recerned are employed, thus the source of antimony suiting stain is more stable to repeated firings may be the trioxide, the source of titania the diin an enamel. However, the color of Naples 7 oxide, and the source of lead may be an oxide or yellow in general is a brownish-yellow or orangea compound yielding an oxide, such as white yellow, far difierent from the lemon-yellow of lead, red lead, litharge, etc., and lead titanate cadmium sulphide. may be employed with the proper amount of anti- In accordance with the present invention, it mony oxide. The materials in properly adjusted now becomes possible to provide a particularly amounts to form the composition are calcined or strong lemon-yellow stain altogether different heated to reaction under oxidizing conditions at 5 from the lead antimony colors described forea suitable temperature, which practically is around 1050-1100 C. Calcination at much lower temperatures does not develop the color sufiiciently, whereas higher temperatures cause the material to sinter to a hard mass. Proper calcination is attained only when the batch and the furnace are maintained at substantially the same temperature throughout the firing cycle. After attaining the proper temperature, it is held constant for several hours to assure complete development of the color.

The following examples are illustrative of the invention:

I. Fifty-seven parts of litharge, 20 parts of antimony oxide, and 20 parts of titanium dioxide. The mixture is calcined under oxidizing conditions at about 1070 C. A light flufiy brilliant lemon color is attained. This is ready for use as a ceramic stain without further treatment such as ball-milling which is commonly required with colors heretofore.

II. Similarly, 58.2 parts of Pb3o4, 20 of 810203, and 20 of TiOz.

III. Similarly, 66.0 parts of white lead, 20 of Sb203, and 20 Of T102.

IV. Similarly, 228 of red lead, 80 of SbzOs, and 100 of T102.

V. Similarly, 228 of red lead, of $132.03, and 80 of T102.

VI. Similarly, 228 of red lead, 80 of SbzOa, and of TiOz.

VII. Similarly, 200 of red lead, of SbzOs, and 80 of T102.

VIII. Similarly, 350 of red lead, 80 of SbzOz, and 80 of T102.

IX. Similarly, 202 of red lead, 43.2 of Sb2O3, and 54 of TlOz.

X. Similarly, 152 of lead titanate, and 40 of Sb203.

All parts are by weight, in the foregoing examples.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

ILA color composition, substantially, of the molecular formula 4PbO.SbzO5.4TiO2.

2. A color composition embodying PbO about 58.1 per cent, Sb205 about 21.1 per cent, and TiOz about 20.8 per cent.

3. A color composition consisting of the reaction product of red lead about 59.3 parts, antimony trioxide about 19 parts, and titanium dioxide about 20.8 parts, by Weight.

4. A color composition consisting of a combination of PbO 50-70 per cent, Sb205 14-26 per cent, and TiOz 14-26 per cent.

5. A process of making a color composition, which comprises calcining at 1050-1100 C. oxides of lead, antimony and titanium yielding 4PbO.Sb205.4=TiO2.

6. A process of making a color composition, which comprises calcining at 1050-1100 C. a mixture providing PbO about 58.1 per cent, Sb205 about 21.1 per cent, and TiOz about 20.8 per cent.

7. A process of making a color composition, which comprises calcining at 1050-1100 C. red lead about 59.3 parts, antimony trioxide about 19 parts, and titanium dioxide about 20.8 parts, by weight.

8. A process of making a color composition, which comprises calcining at 1050-1100 C. materials to yield a product of the composition PbO 50-70 per cent, SbzOs 14-26 per cent, and T102 14-26 per cent.

WILLIAM D. STILLWELL. 

